The embodiments described herein relate generally to power equipment protection devices and, more particularly, to apparatus employing an insulated plenum for use in diffusing ionized exhaust gases and pressure away from a location of arc generation.
Conventional panelboards provide an electrical distribution apparatus for mounting a plurality of circuit breakers to control electrical distribution from a main to one or more branch circuits. Such panelboards typically comprise a wall-mounted enclosure supporting conductive bus bars and electrical switching apparatus (e.g., without limitation, switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers) electrically coupled to the bus bars.
Circuit breakers are often arranged in conventional panelboard assemblies in adjacent pairs and are connected in an end-opposing, “double-branch” arrangement, to bus bars carrying current of the same electrical phase. Circuit breakers typically have a molded plastic housing enclosing at least one pair of separable contacts. When the separable contacts are opened, under overload, short circuit or fault conditions, an arc is created which is accompanied by the generation of ionized gases. The ionized gas temperatures can reach or exceed 20,000° C., which can vaporize the conductors and adjacent equipment. Moreover, an arc flash can release significant energy in the form of heat, intense light, pressure waves, and/or sound waves, sufficient to damage the conductors and adjacent equipment.
Such ionized gases are conventionally discharged through exhaust vent openings arranged in the circuit breaker housing and, when discharged from one circuit breaker within the double-branch arrangement, could transfer to the other adjacent circuit breaker, or to the bus bar conductors, resulting in a phase-to-phase electrical fault. The ionized gases could also cause a phase-to-ground failure with the metallic panelboard enclosure within which the circuit breaker is mounted.
Known prior art panelboard assemblies employ barriers between the opposing poles of a pair of double-branch mounted, spaced-apart circuit breakers in a multi-phase power system to prevent a phase-to-phase electrical fault caused by ionized exhaust gases discharged from one circuit breaker phase from reaching or contacting other phase conductors in the power system.
Although some prior art panelboards have included barriers to protect the phase conductors from the discharged ionized gases, these barriers typically aim to prevent the flow of the exhaust gases past the barrier and do not segregate or direct the ionized exhaust gases into an insulated chamber or plenum. Additionally, other prior art barriers use more complex multiple piece barrier arrangements, which increase cost. There is a need therefore, for an improved simple, robust, and inexpensive, insulative barrier having minimal parts, installable in a panelboard, and capable of diffusing and effectively controlling discharged ionized gases.
Accordingly, there is room for improvement in circuit protective systems having an insulative plenum for electrical switching apparatus and panelboard assemblies.